Bose Lifestyle PS 28 Troubleshooting Manual
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Bose Lifestyle PS 28 Troubleshooting Manual

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Table of Contents

Safety Information.............................................................................................................................2
Electrostatic Discharge Senstitive (ESDS) Device Handling ........................................................2
Specifications ....................................................................................................................................3
Theory of Operation .................................................................................................................... 4-21
Setting up a computer to issue TAP commands ..........................................................................22
Placing the Bass Module into TAP Mode ......................................................................................23
Figure 1. DIP switch Up/Down orientation ......................................................................................23
Equalizer Programming Method ....................................................................................................23
Scope Photos ............................................................................................................................ 24-25
Integrated Circuit Diagrams ..................................................................................................... 26-30
THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION OF
BOSE
®
CORPORATION WHICH IS BEING FURNISHED ONLY FOR
THE PURPOSE OF SERVICING THE IDENTIFIED BOSE PRODUCT
BY AN AUTHORIZED SERVICE CENTER OR OWNER OF THE BOSE
PRODUCT, AND SHALL NOT BE REPRODUCED OR USED FOR ANY
OTHER PURPOSE.
Contents
PROPRIETARY INFORMATION
1
PS18/28/35 Troubleshooting Guide

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  • Page 1: Table Of Contents

    THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION OF BOSE ® CORPORATION WHICH IS BEING FURNISHED ONLY FOR THE PURPOSE OF SERVICING THE IDENTIFIED BOSE PRODUCT BY AN AUTHORIZED SERVICE CENTER OR OWNER OF THE BOSE PRODUCT, AND SHALL NOT BE REPRODUCED OR USED FOR ANY OTHER PURPOSE.

  • Page 2: Safety Information

    ® CAUTION: THE BOSE PS 28 AND PS 35 POWERED SPEAKER CONTAINS NO USER-SER- VICEABLE PARTS. TO PREVENT WARRANTY INFRACTIONS, REFER SERVICING TO...

  • Page 3: Specifications

    PS18/28/35 Troubleshooting Guide Specifications Mechanical Dimensions: Module: 8.0" W x 23.0" D x 16.0" H (20.32 x 58.42 x 40.64 cm) Satellite: 3.1" W x 4.0" D x 6.02" H (7.8 x 10.2 x 15.7 cm)  2.2" W x 8.0" D x 2.6" H Jewel Cube speaker: (39.4 x 20.3 x 6.6 cm)

  • Page 4: Theory Of Operation

    1. Power Supply, Switch-Mode Audio Tracking 1.1 Introduction ® There is a growing demand for power in home theater systems. Traditionally a Bose home theater system uses an unregulated linear power supply to power multiple linear audio amplifiers. The power supply is typically based on a line-frequency transformer and the audio amplifiers are either Class-B or Class-G linear amplifiers.
  • Page 5 PS18/28/35 Troubleshooting Guide Theory of Operation AC power comes from line source to an EMI filter first, which prevents noise generated by high frequency switching from flowing back to the line source. A bridge rectifier BR1 converts AC power into DC power. There are three versions of the power supply; US, Euro, and Dual. For the US version, the bridge rectifier BR1 is configured to a voltage doubler rectifier.
  • Page 6 PS18/28/35 Troubleshooting Guide Theory of Operation The IC has two enable pins, one of which (pin-8) disables the operation while the other (pin-9) enables the operation. A voltage pulse higher than 0.6V at pin-8 shuts down the IC and a voltage pulse higher than 1.2V at pin-9 wakes up the IC.
  • Page 7 PS18/28/35 Troubleshooting Guide Theory of Operation 1.4 High-frequency Resonant Converter This section describes the theory of operation for a high-frequency half-bridge resonant DC-DC converter, the heart of the power supply. Figure 5 shows its detailed circuit, where the high-fre- quency transformer is represented by a leakage inductor Llk, a magnetizing inductor Lm, and an ideal step-down transformer.
  • Page 8 PS18/28/35 Troubleshooting Guide Theory of Operation The parameters of capacitor C115 and inductor Llk are selected in such a way that its resonant frequency is lower than the range of switching frequencies. In other words, the switching frequency is always above the resonant frequency. The resonant circuit is operated in inductive mode. Two capacitors C113, C114 are added in parallel with the two MOSFET switches to slow down the voltage transition across the two switches.
  • Page 9 PS18/28/35 Troubleshooting Guide Theory of Operation 1.5 Feedback Control Circuit The feedback circuit controls the above power converter in such a way that its output voltage follows or tracks the power supply control (PSC) signal. This section describes the feedback circuit shown in Figure 9.
  • Page 10 PS18/28/35 Troubleshooting Guide Theory of Operation Figure 11. Over-temperature and AMP_FAULT protection circuit A positive-temperature-coefficient (PTC) resistor RT100 is placed next to a heat sink for two power MOSFETs. When the PTC RT100 is heated up to 125°C by the heat sink, the resistance of the PTC increases dramatically, resulting in a logic-high at the PTC.
  • Page 11 PS18/28/35 Troubleshooting Guide Theory of Operation slow decay of the voltage at the two energy storage capacitors C110, C111. The power down circuit gives the audio power amplifiers enough time to mute before the rail collapses, preventing the speakers from making a pop noise. Figure 13.
  • Page 12 PS18/28/35 Troubleshooting Guide Theory of Operation 2. DSP PCB 2.1 General Overview The DSP board contains the majority of the control and signal processing functionality for the PS28 Powered Speaker. The DSP board receives audio data and SmartSpeaker commands from the head-end via the RJ-45 connector.
  • Page 13 PS18/28/35 Troubleshooting Guide Theory of Operation matic SD254175, that the Sharc, U4, has been schematically broken up into several blocks of similar function/connection pins to make the schematic easier to follow. The DSPs have no internal program ROM, so all executable program code must be stored in external ROM.
  • Page 14 PS18/28/35 Troubleshooting Guide Theory of Operation The unit boots into SmartSpeaker mode by default and can be put into TAP mode via two different methods: • Send out the following 4 bytes using a RS-232 terminal (4800 baud, 8 bits, no parity, 1 stop bit): 0x01,0xFF,0xAA,0x54.
  • Page 15 PS18/28/35 Troubleshooting Guide Theory of Operation 2.7 LEDs Sheet 8 of SD254175 The amber and green LEDs on the DSP board serve to provide a wealth of information about the status and operation of the DSP board. The following is a summary of the various possible states of the LEDs and a functional description of the state(s) represented.
  • Page 16 PS18/28/35 Troubleshooting Guide Theory of Operation 2.10 Bass and Satellite Clip Detect Inputs Sheet 3, 8 of SD254175 The Power Amplifier board has circuitry to predict signal clipping of the amplifier outputs on posi- tive going peaks. These events are separately sensed for the Bass channel and the satellite channels (all 5 are logic-OR’d together) and brought on to the DSP board through J604.
  • Page 17 PS18/28/35 Troubleshooting Guide Theory of Operation Serial audio data comes out of U2 on pins 10, 16, 17, and 18. The audio master clock, SPDIF_256FS clocks at 256 times the audio sample rate. The analog receiver section of the CS8415A operates off the +5V supply rail and the digital/logic sections operate off the +3.3V supply rail.
  • Page 18 PS18/28/35 Troubleshooting Guide Theory of Operation one section of U402 is used to buffer a 2.3V reference derived from the regulated 5.0V supply. This external analog reference voltage is marked as “DC_BIAS” on the schematic. The codec has a mute control output, /MUTEC, which it asserts (active low) immediately whenever it detects problems with incoming clocks or data and the outputs may become unpredictable (i.e., pops, clicks, noise, etc.).
  • Page 19 The compressed format audio streams (AC-3 and DTS) are decoded by a separate DSP from the Sharc used to perform the ® Bose processing. 2.18 Power On and Boot Up Sequence of Events When power is first applied, the Sharc boots and loads/executes the first set of instructions found in the FLASH memory.
  • Page 20 PS18/28/35 Troubleshooting Guide Theory of Operation Assuming that the POST is successful, the Sharc sets up the registers for the S/PDIF receiver (U2), codec (U401), and Compressed Audio Decoder (U103) to function as needed. The PSC_PWM control is set to its minimum value, the amplifier Mute control lines LRCB_MUTE and LSRS_MUTE are asserted (low).

  • Page 21: Theory Of Operation

    PS18/28/35 Troubleshooting Guide Theory of Operation 3.3 Clip Detect Circuit The satellite clip detect circuit consists of diodes D401, D101, D301 and transistors Q3 and Q4 (upper left section of sheet 2). Q4 and Q3 are normally OFF. At high volume levels, if any one of the satellite amplifier outputs comes within 2 volts of the positive power supply rail, Q4 and Q3 turn ON and signal the DSP board through SAT_CLIP that compression is needed.

  • Page 22: Setting Up A Computer To Issue Tap Commands

    PS18/28/35 Troubleshooting Guide Setting up a computer to issue TAP commands 1. Open a terminal window. Click: Start/Pro- 4. In the “COM1 Properties” window, make the gram/Accessories/Hyperterminal/Hyperterminal selections in the various fields as shown. 2. In the “Connection Description” window, type the name “LS28, 35 bass module test”...

  • Page 23: Placing The Bass Module Into Tap Mode

    PS18/28/35 Troubleshooting Guide Placing the Bass Module into TAP Mode Place all four DIP switches to the down position before returning the unit to the customer 1. Place the bass module into TAP mode 2. Verify the bass module communicates in TAP mode.

  • Page 24: Scope Photos

    PS18/28/35 Troubleshooting Guide Scope Photos (x10 probe used) DSP PCB, U2 Pin 10, S/PDIF _256FS DSP PCB, U103 Pin 25, S/PDIF _64FS DSP PCB, U2 Pin 16, S/PDIF _64FS DSP PCB, U103 Pin 26, S/PDIF LRCLK DSP PCB, U2 Pin 17, LRCLK DSP PCB, U103 Pin 30, 10 MHZ (7.5 MHZ Clock) DSP PCB, U2 Pin 18, SERIAL DATA OUTPUT...

  • Page 25: Scope Photos

    PS18/28/35 Troubleshooting Guide Scope Photos (x10 probe used) DSP PCB, U103 Pin 42, LRCLK DSP PCB, Q6 Collector, Serial Data XMT. DSP PCB, U103 Pin 43, _64FS DSP PCB, U3 Pin 13, SERIAL DATA RCV.

  • Page 26: Integrated Circuit Diagrams

    PS18/28/35 Troubleshooting Guide Integrated Circuit Diagrams CS8415A, SPDIF receiver part number 254193-001 IN+ (1) IN- (1) IN- (2) IN+ (2) MUTE Truth Table OUTPUT (2) OUTPUT (1) TDA7265, power amp, 2 x 25W part number 256084-001 And gate, quad 2-input, CMOS part number 256124-001 Connection Output 2...
  • Page 27 PS18/28/35 Troubleshooting Guide Integrated Circuit Diagrams DSP ADSP21065LKS part number 254191-001 Type Function ADDR 23-0 I/O/T External Bus Address. The ADSP-21065L outputs addresses for external memory and peripherals on these pins. In a multiprocessor system the bus master outputs addresses for read/writes of the internal memory or IOP registers of other ADSP-21065L.
  • Page 28 PS18/28/35 Troubleshooting Guide Integrated Circuit Diagrams DSP ADSP21065LKS part number 254191-001 Type Function FLAG 11-0 I/O/A Flag Pins. Each is configured via control bits as either an input or an output. As an input, it can be tested as a condition. As an output, it can be used to signal external peripherals.
  • Page 29 PS18/28/35 Troubleshooting Guide Integrated Circuit Diagrams DSP ADSP21065LKS part number 254191-001 Type Function BSEL EPROM Boot Select. When BSEL is high, the ADSP-21065L is configured for booting from 8-bit EPROM. When BSEL is low, the BSEL and BMS inputs determine booting mode. See BMS for details. This signal is a system configuration selection which should be hardwired.
  • Page 30 PS18/28/35 Troubleshooting Guide Integrated Circuit Diagrams DSP ADSP21065LKS, part number 254191-001 Type Function SDCLK 1-0 I/O/S/T SDRAM 2x Clock Output. In systems with multiple SDRAM devices connected in parallel, supports the corresponding increase clock load requirements, eliminating need of off-chip clock buffers. Either SDCLK 1 , or both SDCLKx pins can be tri- stated.

  • Page 31: Troubleshooting Guide

    Troubleshooting Guide ® Lifestyle PS 28 and 48 ® Digital Acoustimass Powered Speaker 120V, 230V, Dual Voltage (US, UK, AUS, MIL) © 2003 Bose Corporation Troubleshooting Guide Rev 00 06/03 Part Number 268795-TS Electronic Copy Only...
  • Page 32 Specifications and Features Subject to Change Without Notice Bose Corporation The Mountain Framingham Massachusetts USA 01701 P/N 268795-TS REV. 00 06/03 (H) http://serviceops.bose.com...

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